Univariate and multivariate analyses of PFS and OS were performed by COX regression model, and considering factors included age, ECOG, thrombocytopenia CTCAE grades, menstrual status, treatment lines, HR status, HER2 status, number of metastatic sites, metastatic sites, treatment lines, anti-HER2 treatment, prior surgery, BMC status, pretreatment LDH level, pretreatment dNLR level, pretreatment LNI value, LDH and dNLR changing trend. The gene discussed is ERBB2; the disease is Thrombocytopenia.